Leather rolling machine



1969 B. PLECHAC ETAL LEATHER ROLLING MACHINE //7 Van 70/6 Filed Oct. 19, 1966 h V, a M mw w w dy M e M 7?" uk wi V t m ram 5 M m Filed Oct. 19, 1966, Ser. No. 587,908 Claims priority, application Czechoslovakia, Oct. 20, 1965,

6,319/65 U.S. CI. 69-46 Int. Cl. c141) 1/34; Fb 15/14, 7/00 9 Claims ABSTRACT OF THE DISCLOSURE A rolling machine particularly for rolling sheet material such as leather. The rolling machine has at least one rolling disk for mechanically compacting the leather. The rolling disk is supported for rotary movement by bearings which in turn are carried by a support means providing through spring means a cushioned support for the rolling disk in such a way that the latter will smoothly engage the edges of the leather sheet material. A hydraulic pressure-fluid device coacts with the disk to press the latter against the leather sheet material.

The present invention relates to leather rolling machines.

More particularly, it relates to that type of leather rolling machine in which one or more rolling disks are applied with pressure against the leather sheet material in order to compress the latter.

The machines which are used for mechanically compacting leather in this way are either of the type whereby the rolling disks are carried by a suitable carriage structure movable along a bridge-type of supporting frame so that the disks are translated while they rotate around their axes to compact the leather, or of the type whereby the leather sheet material travels through the machine engaging successive rolling disks thereof, so that with such through-rolling machines the disks rotate about their axes but do not travel horizontally. In both types of machines a mechanical or pneumatic pressure system is used in combination with hydraulic adjustment and control of the mechanical structure for the purpose of achieving the required pressure.

In these rolling machines, the leather sheet material is compacted with a relatively heavy rolling disk having a diameter on the order of from 400 to 600 mm. The cylindrical portion of the disk surface is made of metal having a Brinell hardness of about 500, with the cylindrical exterior surface of the rolling disk being ground and polished for the purpose of providing on the leather, particularly at the grain side thereof, a smooth glossy surface.

Rolling disks of this type are rotatably carried by shafts which rotate in suitable bearings which are vertically shiftable in suitable guides carried by the carriage in the case of the one type of machine wherein the disks are moved horizontally back and forth so as to gradually roll the leather along strip-shaped areas corresponding to the active portion of the rolling disk which engages, the leather, whereas in the through-rolling type of machine the leather is moved through the machine while acted upon by disks which are also supported in bearings that are guided for vertical movement. The speed of rotation of the rolling disk, in the movable carriage type of machine, is determined by the speed of the translational movement of the carriage which carries the disk, and in this type of machine the speed of movement of the carriage is maintained in a range of from 0.2 to 0.4 meter per second.

atent In the through-rolling type of machine the plurality of rolling disks are situated so that while the leather sheet material passes continuously through the machine the several disks have mutually overlapping active areas of contact with the leather sheet material so that in this way the leather sheet material is rolled over its entire surface during one pass of the leather sheet material through the machine. It is to be noted that in the through-rolling type of machine the disks have their bearings also mounted on carriages, but in this case the carriages are fixedly mounted on the machine frame while the leather sheet material is supported on rotary metallic cylinders which rotate at a circumferential velocity equal to the circumferential velocity of the rolling disks.

The pressure with which the dis-ks act on the leather can be adjusted up to approximately 250 kilograms per mm. (kilogram force) of effective width of the rolling disk. The total pressure of each rolling disk is derived either directly from relatively heavy springs or from a system of springs which coact with a leverage assembly. Such systems include springs that coact, for instance, with a system of angle or bell-crank levers. Relatively low pressures are sometimes applied pneumatically. The required pressure of the rolling disk is adjusted mechanically or hydraulically by changing the length of the springs.

The disadvantage of the known mechanical pressure control systems for controlling the pressure of the rolling disks resides in the arrangement of adjusting wheels which are manually turned and are not readily accessible to the operator when the operator is situated at a normal operating station. These structures require the operator to leave the latter station and, depending upon the desired final quality of the rolled leather, to make fine adjustments of the rolling pressures of the several individual rolling disks, so that the pressure will be at least substantially uniform over the entire leather sheet material to avoid grooved or striped areas in the rolled leather surface. Of course, any irregularities in the rolled surface of the leather greatly reduces the value thereof.

A further disadvantage of the conventional leather rolling structure which can roll with pressures of from to 250 kilograms per mm. of width of the rolling disk resides in the fact that the operator does not know the precise value of the rolling pressure, even where there is a hydraulic adjustment of the force exerted by the pressure springs. The operator does not know the actual pres sure because of the operating characteristics of these springs, these characteristics depending upon the unequal and variable thickness of the leather sheet material. As a result of this latter factor, it is necessary, before the leather sheet material is rolled, to classify and sort the leather sheets in accordance with their thickness, for the machines require different adjustments for different thicknesses. The diflerent adjustments are diflicult to provide and involve tedious work which cannot be avoided since the rolling would otherwise take place in a non-uniform manner resulting in striped, grooved, irregular rolled surfaces. It is not uncommon to encounter in a single sheet of leather a thickness variation of from 2 to 3 mm., and such thickness differential in a single sheet of leather cannot be compensated by the elasticity of the known systems which control the pressure of the rolling disk. As a result, the elasticity of the pressure-controlling system is not effective and the rolling operations continue under conditions determined by the elasticity of the entire machine frame. This latter factor results in uncontrolled loading of the entire machine, in the formation of irregular, striped or grooved rolled surfaces and, above all, in excessive wear of the machine, with the results that lworn parts thereof must frequently be changed and failures of machine parts are encountered from time to time. These latter drawbacks, particularly in the case of throughrolling machines of high output, result in considerable losses and premature inoperativeness of machines of this type.

Because of the above referred to conditions the mechanical pressure systems require frequent and careful lubrication. The number of lubricating areas is extremely high, there being as many as 150 lubricating areas in through-rolling machines, and great demands are made on the care and responsibility of the operator of the machine to maintain it in good running order.

It is accordingly a primary object of the present invention to provide a leather-rolling machine which will eliminate all of the above mentioned drawbacks.

In particular, it is an object of the invention to provide for a leather-rolling machine a construction which will enable the rolling disks thereof to act uniformly on the leather sheet material without requiring any of the precise adjustments and without having the other drawbacks referred to above.

Another object of the invention is to provide a leatherrolling machine which will produce a uniform rolling pressure on the leather sheet material irrespective of variations in the thickness thereof, so that on the one hand the drawbacks encountered because of thickness variation of a given sheet of leather are avoided and on the other hand it becomes completely unnecessary to classify and sort the leather sheet material according to diiferent thicknesses before the rolling thereof. The elimination of this latter requirement also carries with it the elimination of requirements for adjusting the machine to a particular thickness of leather sheet material.

It is a further object of the present invention to provide a machine which will have a smooth transition of the disks onto and from the leather sheet material so that the edges of the leather sheet material are not excessively compressed or crushed.

In addition, it is an object of the invention to provide a construction which can be used either with a throughrolling type of machine or with a machine in which the rollers are carried by horizontally movable carriages.

Also, it is an object of the invention to provide a construction which is exceedingly simple and rugged as well as highly reliable in operation.

In accordance with the invention, the leather-rolling machine includes at least one rolling disk and a bearing means supporting the disk for rotation about its axis. A support means supports the bearing means for movements together with the disk in a direction perpendicular to the disk axis, and a hydraulic pressure means acts on the support means to urge the latter together with the bearing means and disk in the direction which is perpendicular to the disk axis. A high-pressure hydraulic control means communicates with the hydraulic pressure means for providing for the latter a high pressure which is controlled by the hydraulic control means to produce on the leather the required rolling pressure, and a lowpressure hydraulic control means communicates with the high-pressure hydraulic control means for controlling the high-pressure hydraulic control means.

The invention is illustrated by way of example in the accompanying drawings which form part of this application and in which:

FIG. 1 is a partly sectional schematic fragmentary elevation of one possible embodiment of a leather-rolling machine according to the invention; and

FIG. 2 fragmentarily illustrates part of the structure of FIG. 1 in connection with the setting-up of a gap between the leather-rolling disk and the structure which supports the leather.

The structure which is shown in the drawings can be used either in a through-rolling type of machine or in a machine where the disks are carried by horizontally movable carriages. FIG. 1 illustrates one of several rolling disks 1 all of which are supported in the same way, so

that only the structure used in connection with one of the disks is shown in the drawings and described below. The disk 1 has an active peripheral width a, and it may fixedly carry at its opposite sides coaxial shafts 2, but in the illustrated embodiment a single shaft 2 extends through and fixedly carries the disk, this shaft 2 having its axis coinciding with the disk axis.

The disk 1 is supported by a bearing means for rotary movement, and this bearing means includes ball bearings 3 which receive the end portions of the shaft 2 and which include components having surfaces which slidably engage each other and form parts of spheres, so that the bearing means 3 of the invention is capable of supporting the disk 1 not only for rotation about its axis but also for swinging movement with the axis of the disk swinging in a vertical plane so that the active periphery of the disk can adapt itself automatically to any sloping of the rolled surface.

A support means supports the bearing means 3 and the disk 1 for movement perpendicularly to the disk axis, this movement being vertical in the illustrated example where the disk has a horizontal axis. This support means includes a pair of elongated substantially rigid struts 4 which are operatively connected with the bearings 3 so as to carry the latter in the manner shown schematically in FIG. 1. The support means also includes a spring means 6 in the form of a pair of compression springs situated beneath the bearings 3 and engaging the struts 4 at the lower ends thereof, at the portions thereof which surround and carry the bearings 3, these springs 6 being compression springs which urge the struts 4 upwardly.

A hydraulic pressure means is provided for urging the support means downwardly in a direction perpendicular to the disk axis, and this hydraulic pressure means includes hydraulic cylinders 5 which are respectively situated over the struts 4.

The compression springs 6 are situated in hollow cups 7 which are externally threaded and which are received in internally threaded rings that are carried by a frame 8 of the machine, although in the case of a machine of the type where the rollers are horizontally moved in translation, the frame 8 would be part of a carriage frame. The externally threaded cups 7 are threaded into threaded bores of the frame 8 or into interiorly threaded rings fixedly carried by the frame 8, so that the elevation of the cups 7 and in this way the compression of the springs 6 can be adjusted, thus adjusting the force with which the spring means 6 urges the disk 1 upwardly, as viewed in FIG. 1.

At their top ends each strut 4 threadedly carries an externally threaded sleeve 9 which thus can be adjusted with respect to the strut 4. The sleeve 9 surrounds a spring means 10 in the form of a second compression spring situated between each strut 4 and the cylinder 5 thereover and urging the strut and cylinder apart from each other.

The hydraulic pressure means includes, in addition to the cylinder 5, a piston 11 which is fluid-tightly slideable in the interior of the cylinder 5 and which includes a piston rod 12 that extends upwardly beyond the cylinder 5 through an exteriorly threaded sleeve .13 which is threaded to the top end of each cylinder 5. The upper end portion of each piston rod 12 extends through an opening of the frame 8 which can be part of the sationary machine frame or which can be part of a horizontally movable carriage frame, and the upper end portion of each piston rod 12 is exteriorly threaded and carries nuts 14 and 15 by means of which the piston 1.1 can be adjustably fixed in elevation with respect to the frame 8.

Each piston 11 together with its piston rod 12 are axially bored as to provide communication between the interior of the cylinder 5, beneath the piston 11, and a high-pressure hydraulic control means A which communicates with the upper end of each piston rod 12. This highpressure hydraulic control means A in turn communicates with a low-pressure hydraulic control means B, and the pair of control means A and B include a hydraulic multiplier 16 which serves to multiply the pressure of the lowpressure control means B so as to provide the higher pressure of the high-pressure control means A.

This multiplier includes the piston .17 which is slidable in the portion of multiplier 16 which forms a cylinder of relatively large diameter, and the piston 17 is coaxially fixed to a plunger 18 forming a second piston of a diameter substantially smaller than that of the piston 17 and fluid-tightly slidable within an elongated cylinder of smaller diameter of the multiplier 16, as indicated schematically in FIG. 1. Therefore, as is well known, the relatively low unit pressure acting on the large piston 17 will be converted into a relatively high unit pressure provided by the plunger 18 of relatively small diameter.

The high-pressure control means A includes a conduit extending from the multiplier 16 to the top ends of the pair of piston rods 12 shown in FIG. 1, and in addition this high-pressure control means includes a pressure gauge 19 by means of which the operator can at any time see the pressure of the high-pressure control means.

The low-pressure control means B has a conduit 23 communicating with the multiplier 16 beneath the piston 17 thereof and communicating with a pressure gauge 20 which lets the operator know at any time the low pressure of the low-pressure control means B. In some cases it is possible to provide the required pressure by means of a hydraulic accumulator which can be filled by a handoperated pump. However, in the illustrated example the low-pressure control means B includes the adjustable relief valve 2.1 and the conduit 22 which receives the hydraulic liquid under pressure from a suitable unillustrated pump and delivers this liquid through the conduit 23 into the multiplier 16 beneath the piston 17 thereof. The pump is not illustrated since it is conventional, and, if desired, the supply conduit 22 can communicate with any other suitable source of hydraulic liquid under pressure.

The multiplier is bypassed by a conduit 24 which communicates with both of the control means A and B, and the valves 25 and 26 can be opened for the purpose of filling both of the circuits of both hydraulic control means, valve 25 being carried by the conduit 24 while the valve 26 is carried by the conduit 23. During normal operation the valve 26 is open while the valve 25 is closed.

The adjustable relief valve 21 is bypassed by a conduit 27 which com-municates with the conduit 23 as well as with a low pressure return-flow conduit 29 which communicates with a suitable tank or other reservoir from which the liquid is pumped by the unillustrated pump into the supply conduit 22. The bypass conduit 27 is provided with a valve 28 which is opened at the same time as the valves 25 and 26 for the purpose of quickly emptying the hydraulic circuits. During normal operation the valve 28 is closed, so that during the normal operation of the machine valves 25 and 28 are closed while valve 26 is open, and of course the valves controlling the flow to the pressure gauges are also open. The excess liquid acts in accordance with the adjustment of the valve 21 to open the latter and return through the conduit 29 to the tank and then to the suction side of the pump which continuously circulates liquid through the low pressure system.

In the case of that type of machine where the rolling disk is carried by a horizontally shiftable carriage, the leather is held on a table 30 which is fixed so as to receive the sheet of leather 31 thereon, and the roller 1 is displaced over the upper surface of the leather sheet 31. In the case of a through rolling machine, however, the support 30 for the leather sheet 31 is in the form of a rotary cylinder against which the leather 31 is supported as it passes through the machine with the leathersupporting cylinder and rolling disk 1 both rotating simultaneously in opposite directions as the leather sheet material is advanced through the machine.

During operation of the machine the disk 1 constantly presses against the leather sheet material 31 so as to roll the latter. This pressure of the disk 1 against the sheet material 31 is derived by way of the strut 4 and the cylinder 5 of the hydraulic pressure means, the required pressure being derived from the pressure in the closed high-pressure hydraulic circuit formed by the high-pressure control means A. During normal operation the clearance distance x between the cylinder 5 and the top end of the sleeve 9 is eliminated so that the cylinder 5 directly engages the sleeve 9 which is threadedly carried by the strut 4, and of course the spring 10 at this time is compressed to the maximum extent. The hydraulic pressure acts at a certain amount of kilograms per mm. of active width a of the disk 1, and it is exerted by the entire hydraulic control system which includes the independent control circuits A and B. In the low-pressure hydraulic means B, the pump or other source of fluid pressure, which may if required be a central supply source, uninterruptedly delivers the pressure liquid by way of the conduits 22 and 23 into the multiplier 16 in which the pressure is increased through the piston 17 and plunger 18, so that the required high pressure is available at the high-pressure control means A. The hydraulic pressure in this circuit acts in the cylinder 5 to urge the latter downwardly with respect to the piston 11 so as to press downwardly on the nut 9 and the strut 4, at each side of the disk 1, so that the latter is urged against the sheet 31 which is thus rolled with the required pressure. The excess oil or other hydraulic liquid in the low-pressure hydraulic control means B flows through the relief valve 21 and the return flow conduit 29 back into the tank, sump, or other reservoir for the hydraulic liquid.

The operator can at any time check the pressure in the low-pressure control means B by way of the pressure gauge 20, while the pressure gauge 19 permits the operator to check on the pressure in the high-pressure control means A. The ratio between these pressures is determined by the ratio between the areas of the piston 17 and plunger 18 of the multiplier 16. It is possible to adjust the required rolling pressure by a simple adjustment of the valve 21, and a check on the adjustment is immediately derived by way of the pressure gauge 19.

After the pressure has been adjusted, the pressure in both of the control circuits A and B will remain constant during the entire period of operation of the machine even if the thickness s of the leather sheet material 31 varies from the minimum thickness determined by the pre-set gap 8, shown in FIG. 2, and referred to further below, and the value where the thickness s is equal to y, which is the distance or stroke through which the cylinder 5 can move upwardly before its bottom end engages the piston 11. The machine is initially set so as to provide a certain maximum distance y for the maximum thickness of sheet material to be treated, and this distance y may be selected so as to be on the order of 20 or even 25 mm., taking into consideration the possibility that a pair of adjoining leather sheets may overlap. Thus, the machine of the invention is capable of rolling leather sheet material having almost any arbitrary thickness without requiring any sorting or classification of the sheet material prior to rolling thereof and of course without requiring repetitious adjustments of the machine so as to accommodate it to the particular thickness of the sheet material which is to be worked on. The initial adjustment of the piston rod 12 so as to determine the elevation thereof, by means of the nuts 14 and 15, is carried out only during the initial installation of the machine. If desired, after the initial adjustment of the machine the gap S shown in FIG. 2 can be zero, and in this case the disk 1 would directly engage the table or rotary cylinder which supports the leather sheet material, However, it may be preferred that the disk 1 never come into contact with the table or rotary supporting cylinder, and for this purpose the value S shown in FIG. 2 can be set to 0.5 mm., for example, so that when there is no sheet material in the machine, the rolling disks will not engage the sheet-supporting structure.

In order to provide the adjustment for the gap S the externally threaded cups 7 are turned with respect to the frame -8 so as to adjust the force of the springs 6 which carry the full weight of the disk 1 together with the hearing means and the struts 4, as well as the elements 9 and springs 10, and with this adjustment of the springs 6 it is possible for them to support all of the latter structure at such an elevation that when there is no leather in the machine the rolling disks will be situated at a given relatively small distance from the table or cylinder 30, this distance being equal to the gap S shown in FIG. 2.

It is to be noted that the supporting springs 6 also act to damp the downward movement of the disk 1 and the structure which carries the latter when the sheet material 31 moves beyond the disk 1, so that there no longer is any sheet material beneath the latter. The spring means formed by the springs 10 act to maintain a yieldable elastic interconnection between the cylinder 5 and the strut 4 during movement of these elements toward and away from each other. It is to be noted that the clearance distance x between the ring 9 and the bottom end of the cylinder 5 can also be adjusted in accordance with the minimum thickness of the leather sheet material, or it can simply remain at all times at a given constant value. This clearance distance x together with the action of the springs 6 provides a smooth initial contact between the disk 1 and the leather so that crushing of the edge of the leather is avoided. The initial contact of the disk and the leather is gradual and smooth since the entire weight of the rolling disk and the components connected thereto is supported by the springs 6 until the moment when the rings 9 engage the bottom ends of the cylinders 5, respectively, whereupon the hydraulic pressure of the :high pressure hydraulic control means delivers the full rolling force to the disk 1. The disk I automatically adjusts itself in elevation as well as horizontally, in the direction of the axis of the :disk, so as to accommodate itself to the actual thickness of the leather sheet material, because the disk is symmetrically supported at both sides and is symmetrically acted upon by the pair of hydraulic cylinders 5 in which there are equal pressures derived from the high-pressure control means A. Furthermore, the use of the bearings 3 provided with the slide surfaces which form part of spheres enable swinging movements to be provided which permit the disk to adapt itself to the surface of the sheet material.

At the end of the contact between the leather and the disk 1, there is also a gradual reduction in the force of the disk on the leather avoiding crushing of the edge thereof, since as the leather moves beyond the disk 1, the disk 1 together with the struts 4 and the sleeves 9 as well as the cylinders 5 all move downwardly, but this motion is terminated for the cylinders 5, in accordance with the pre-set clearance x, by engagement of each threaded sleeve 13 with the top end of the piston 11 which is of course situated at a fixed elevation by the connection of each piston rod 12 through the nuts 14 and 15 to the frame 8. At this time there is no hydraulic pressure acting on the disk 1 whose weight is carried by the springs 6.

It is possible to achieve substantially the same result by suspending a hydraulic cylinder from the frame 8 of the machine, instead of by fixedly connecting the piston rod 12 thereto, in which case the piston rod can be movably support-ed in the adjustable sleeve 9 of the strut 4. The illustrated structure is preferred, however, because it is simpler.

Among the advantages of the structure of the invention is the fact that the disk 1 can be placed in and out of contact with the leather sheet material at moments when there is no pressure acting to urge the disk 1 against the sheet material. This result is achieved by the adjustment of the clearance x between the hydraulic cylinders 5 and the sleeves 9 of the struts 4. Of course, this latter clearance will be determined in accordance with the minimum thickness of the leather sheet material. The accommodation of the machine to leather of maximum thickness is derived by way of the clearance x and the stroke of the cylinder which is determined by the setting of the piston rod, and this latter setting is carried out at the initial installation of the machine, as pointed out above.

We claim:

1. In a leather rolling machine, at least one rolling disk, bearing means supporting said disk for rotary movement about its axis, support means operatively connected to said bearing means and supporting the latter for movement together with said disk perpendicularly to the axis thereof, hydraulic pressure means coacting with said support means for urging the latter in a direction perpendicular to the axis of said disk, high-pressure hydraulic control means communicating with said hydraulic pressure means for controlling the latter to exert a given pressure on said support means, low-pressure hydraulic control means communicating with said high-pressure hydraulic control means for controlling said high-pressure hydraulic control means, said support means including a strut operatively connected with said bearing means, said hydraulic pressure means including a hydraulic cylinder, 2. piston in said cylinder, and a frame on which said piston is mounted, said cylinder being movable with respect to said piston and said piston and cylinder having a common axis perpendicular to the axis of said disk, and spring means situated between said strut and cylinder for urging said strut and cylinder apart from each other.

2. The combination of claim 1 and wherein an adjusting means is operatively connected with said frame and piston for adjusting the position of the latter on said frame.

3. The combination of claim 1 and wherein said support means also includes a spring means supporting said bearing means and urging the latter in a direction opposed to the direction in which said bearing means is urged by said hydraulic pressure means.

4. The combination of claim 3 and wherein an adjusting means is operatively connected with the spring means which supports said bearing means to adjust the latter spring means.

5. The combination of claim 3 and wherein said bearing means includes bearing members at least part of which have the configuration of parts of a sphere for supporting said disk for swinging movement as well as for rotary movement about the disk axis.

6. The combination of claim 1 and whie'rein a spring means coacts with said bearing means for urging the latter in a direction opposite to that in which said support means is urged by said hydraulic pressure means.

7. The combination of claim 1 and wherein a pressure multiplier forms part of and interconnects said highpressure and low-pressure hydraulic control means for multiplying the pressure of said low-pressure control means so as to provide the higher pressure of said highpressure control means.

8. In a leather rolling machine, at least one rolling disk, bearing means supporting said disk for rotary movement about its axis, support means operatively connected to said bearing means and supporting the latter for movement together with said disk perpendicularly to the axis thereof, hydraulic pressure means coacting with said support means for urging the latter in a direction perpendicular to the axis of said disk, high-pressure hydraulic control means communicating with said hydraulic pressure means for controlling the latter to exert a given pressure on said support means, low-pressure hydraulic control means communicating with said high-pressure hydraulic control means for controlling said high-pressure hydraulic control means, said disk having a horizontal axis and said support means supporting said disk for vertical movement, spring means situated beneath said bearing means and urging the latter upwardly, said support means including a strut carrying said bearing means and extending upwardly therefrom, said hydraulic pressure means including a hydraulic cylinder situated over said strut, a compression spring situated between said strut and cylinder and urging them apart from each other, a piston situated in said cylinder and extending upwardly beyond the latter, a frame carrying said piston, and a pair of adjusting means one of which is operatively connected with said cylinder for limiting the extent of downward movement thereof with respect to said piston and the other of which is connected with said strut for limiting the extent of downward movement of said oylinder before the latter engages said strut.

9. The combination of claim 8 and wherein a third adjusting means is operatively connected to the spring means 'which is situated beneath said bearing means.

References Cited UNITED STATES PATENTS 1,593,653 7/1926 Elliott 6943 2,205,632 6/1940 Schwarz et al. 100-170 2,334,588 11/1943 Smith 6943 2,399,819 5/1946 Moore 6943 2,532,601 12/1950 Bufiek 6946 2,540,132 2/1951 McMath et al. 6946 ALFRED R. GUEST, Primary Examiner.

US. Cl. X.R. 

